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v0.3.0 — Mutation Testing
What's New
Mutation Testing — Third Validation Layer
After acceptance tests verify WHAT and unit tests verify HOW, mutation testing verifies that your tests actually catch bugs. A project with 100% code coverage can still have a 60% mutation score — meaning 40% of introduced bugs go undetected.
New Skill: atdd-mutate
Mutation testing workflow that:
- Auto-detects your project language and configures the right framework
- Runs mutations, reports score and surviving mutants
- Guides you through killing survivors with targeted unit tests
- Integrates as Phase 6 in the team-based ATDD workflow
New Commands
| Command | Purpose |
|---|---|
/atdd:mutate |
Run mutation testing — detect framework, generate mutants, report score |
/atdd:mutate src/auth/ |
Target a specific module |
/atdd:kill-mutants |
Analyze survivors, write tests to kill them, re-verify |
Supported Frameworks
| Language | Framework |
|---|---|
| JavaScript/TypeScript | Stryker |
| Python | mutmut |
| Java/JVM | PIT |
| C# | Stryker.NET |
| Rust | cargo-mutants |
| Go | go-mutesting |
| Ruby | mutant |
| Scala | Stryker4s |
| Clojure | pitest via lein-pitest |
Team Workflow Integration
Phase 6 added to atdd-team skill — after post-implementation review passes, run mutation testing to verify test quality before declaring the feature done.